1. Field of the Invention
The present invention relates generally to railroad yard switch machines, and more particularly to an improved switch machine which may be electrically operated or manually operated, provides run-through capability, and has fewer moving parts than existing switch machines.
2. Description of the Related Art
Machines using hydraulic, pneumatic, or electrical energy to move railroad switch points to remotely or locally change the route of trains have been used for many years. These devices have been very useful for allowing remote operators to control the movement of trains on main lines and side tracks and also for distribution of railroad cars in railroad switch yards.
Within recent years, the use of powered railroad switch movement devices (switch machines) has increased in railroad switch yards as a means of preventing debilitating strains and back injuries to personnel which sometimes results from use of manually-operated switch movement devices (manual switch stands).
One problem with prior art switch machines is the large number of parts, and especially moving parts, thereby requiring frequent maintenance and repair. In addition, typical switch machines utilize gears which can be damaged by vibration of the switch points as railroad cars roll through the switch. Prior art powered switch machines also typically require two motor control relays to permit reversing the direction of a motor to operate the switch machine in opposing directions. These two such relays needlessly increase repair frequency and maintenance costs.
A further problem with conventional switch machines, whether powered or manual, resides in the back injuries sustained during manual operation of such switches. The strain placed on the lower back of a railroad employee while attempting to operate the switch is substantial, and leads to frequent injuries and disabilities.
Applicant solved a large number of the problems in the prior art by way of the invention described in U.S. Pat. No. 6,164,601. In applicant's earlier invention, an improved switch machine was provided where special locking detection features for high-speed main lines were not required. Applicant's earlier invention also provided a switch machine with fewer moving parts and simpler design than existing technology, permitting maintenance-free operation and lower cost. Applicant's earlier invention was also designed to directly replace most of the popular manual switch stands or machines without need for replacing or moving the switch ties, thereby simplifying installation.
Applicant's earlier invention includes a unique mechanism which allows the switch points to be moved in either direction without having to reverse the direction of the motor thereby only requiring one motor control relay instead of two required by the prior art existing electric switch machines. The mechanical mechanism of applicant's earlier patent for moving the switch points was designed to provide a point moving force which follows a general bell curve, to thereby initiate and complete the switching movement at slow speed, with a higher speed movement in the middle of the switching cycle.
Applicant's earlier invention also contains a spring-loaded mechanical release which will prevent damage to the motor and crank mechanism if the points of the switch are prevented from moving by a foreign object or if a train moves through the switch when the points are in the wrong direction and forces the points to the other position (trailed through or run through). Applicant's earlier mechanical release was designed to cause the vertical shaft to hold the points in position as long as the motor is in its stopped position, regardless of correspondence between the crank mechanism position and the position of the points.
Applicant's earlier invention contained a hand-throw lever device which may be used to disengage the crank mechanism from the vertical shaft to permit manual movement of the switch points if electrical power is lost or the motor or crank mechanism fails. Provision was made to allow the switch points to be locked in position using the hand-throw lever if it is desired to prevent remote movement of the switch points by activation of the motor and crank mechanism.
Although the invention of applicant's earlier patent has met with considerable success, some concern has been raised as to the position of the hand-throw lever when it is manually operated since the lever extends outwardly from the machine. Despite the success of applicant's earlier invention, it is believed that the present invention represents a significant improvement over the earlier invention in that a different spring arrangement is utilized in the instant invention and it is believed that the operation of the hand-throw lever device is much easier than applicant's earlier machine. Further, in the instant invention, there is no need to disengage the cam follower assembly from the orthogonally mounted plate on the shaft as in applicant's earlier invention.